Summary of the execution issues between mysql max and where

Execution problem between mysql max and where

Execute sql:

CREATE TABLE `grades` (
 `id` int(20) NOT NULL AUTO_INCREMENT,
 `student_id` int(20) NOT NULL,
 `subject` varchar(20) COLLATE utf8_bin DEFAULT NULL,
 `grades` varchar(20) COLLATE utf8_bin DEFAULT NULL,
 PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=utf8 COLLATE=utf8_bin;
insert into `grades`(`id`,`student_id`,`subject`,`grades`) values (1,1,'Chinese','80'),(2,1,'Mathematics','89'),(3,2,'Chinese','90');
CREATE TABLE `student` (
 `id` int(20) NOT NULL AUTO_INCREMENT,
 `name` varchar(20) COLLATE utf8_bin DEFAULT NULL,
 PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=utf8 COLLATE=utf8_bin;
insert into `student`(`id`,`name`) values (1,'xiaoming'),(2,'xiaohong'),(3,'xiaobai');

Execution Result:

Execution result 1:

Execution result 2:

Execution result 3:

Execution result 4:

Execution result 5:

It can be seen from this that:

1.max is executed before the where condition,

2. Group by is executed before max

3. When where and group by appear at the same time, the where condition is executed first

Summarize

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